In recent years, transcutaneous electrical nerve stimulation (TENS) has been developed to provide relief of pain without the use of systemic analgesic drugs. Stimulators used for this purpose deliver therapeutic electrical impulses to the skin surface of a living patient through lead wires from the stimulator to body contacting electrodes. Typically, transcutaneous electrical stimulators control at least the therapeutic parameters of electrical pulse width, electrical pulse rate, and electrical pulse amplitude. Sometimes, the same stimulator may have dual controls for operating two separate transcutaneous electrical output channels.
Also in recent years, neuromuscular stimulation (NMS) has been developed to provide muscle re-education (maintenance, strengthening, or rehabilitation) transcutaneously.
Conventionally, the electrical pulse parameters have been controlled in the stimulator using either potentiometers or with momentary contact rocker switches. The latter are shown in coassigned U.S. Pat. No. 4,803,986 (Dufresne et al.), which is hereby incorporated by reference.
For purposes of describing this invention, a "transcutaneous electrical stimulator" includes at least a TENS stimulator, a NMS stimulator, or any other medical stimulator used to deliver therapeutic electrical impulses.
One difficulty with using conventional stimulators is dealing with the problem of setting the various electrical pulse controls for the proper and unique operation of the transcutaneous electrical stimulator for a patient because the stimulator is used therapeutically by untrained personnel. Sometimes, the stimulator is used by a patient apt to alter the controls in ignorance of the effect of such alteration.
The desired therapeutic effect of the electrical impulses can not occur if the controls are not properly set by trained personnel. Unfortunately, misapplication of the stimulator through improper setting of the controls can be painful to the patient at the very location requiring pain relief therapy.
Previously, the operation of electrical switches by a token using a plurality of multiple contact switches for use in dispatching systems has been disclosed in U.S. Pat. No. 3,046,364 (De Kramer et al).
Also, U.S. Pat. No. 4,647,734 (Dana) discloses a key activated switch providing binary coded switching outputs for use with microprocessor based equipment. An arrangement of actuators is also disclosed.
Also, U.S. Pat. No. 3,415,087 (Kramasz et al) discloses a plurality of electrical switches disposed in spaced relation to the cylinder of a pin tumbler lock. A special key is provided wherein one edge has conventional serrations for operating the pin tumbler, and the other edge has a plurality of lobes or notches formed into it which cooperate with a link mechanism that activates on or more of the electrical switches.
None of these prior activities has contemplated the circumstances unique to pain relief therapy using transcutaneous electrical stimulators.